Referring to U.S. Pat. No. 4,736,132, Piezoelectric Mirror and Grating, issued 5 Apr., 1988, described are optical positioning devices comprising piezoelectric body segments with surface portions that rotate by mechanical shear in response to an applied electric potential. Piezoelectric segments of this device shear uniformly because piezoelectric segments are uniformly polarized. Whole body rotation requires support of shear body segments by an extension of an electrode, usually the central electrode. Such support is appropriate for the relatively small forces imposed by the self-weight of each piezoelectric segment and of the optical element portion attached thereto, but is not appropriate for the relatively large forces pertinent to industrial actuators and motors.
Referring to U.S. Pat. No. 4,928,030, Piezoelectric Actuator, issued 22 May, 1990, and U.S. Pat. No. 5,043,621 issued 27 Aug., 1991, described are shear piezoelectric devices that forcefully actuate in a direction parallel to the direction in which one shear face translates relative to an opposite shear face. Surface portions of piezoelectric shear body segments that rotate in the act of shearing are not used other than to provide the mechanical compliance needed for shear deformation. The shear modulus of most ferroelectric ceramic piezoelectric materials is lower than all other moduli.
Referring to Applicant's pending patent Biaxial Transducer, Ser. No. 07/726,441 filed 2 Jul., 1991, described are methods of providing relative strain with negligible stress in the plane between bonded or integrally manufactured bodies, for example, the junction between a shear piezoelectric member and a thickness-mode piezoelectric member. The disclosure teaches methods of varying the piezoelectric shear responsivity radially from an axis and linearly with distance from the axis. Also taught are methods of achieving radially varying responsivity within a piezoelectric shear segment using heat gradients, radiation gradients, material properties gradients, and electrodes having nonhomogeneous electrical properties.
Referring to Applicant's pending Ser. No. 07/708,643, Twisting Actuator (Twister), filed May 31, 1991, described therein are means of providing rotation of a broad surface of an electrodeformable body about an axis parallel to the broad surface by the use, among others, of a radial gradient of responsivity, that is clearly distinct from the linear responsivity gradient of the present invention. Also taught in Applicant's pending 07/803,804 filed Dec. 9, 1991, a Division of 07/708,643, is the use of position sensors to measure a composite of coacting angular and linear accelerations acting on the broad surface, this measurement being clearly distinguished from the measurement of angular acceleration alone by the present invention.
Referring to Applicant's pending patent DC Traveling Wave Motor, Ser. No. 07/492,152 filed Mar. 13, 1990, will issue Feb. 11, 1992 as U.S. Pat. No. 5,087,852, described is a direct current traveling wave motor using face shear waves of a piezoelectric lining of the stator. Waves are generated by the enhancement of electric field intensity due to the presence of rollers in rolling contact with the piezoelectric lining. The slope of a shear wave is highest in the region of the highest field intensity. Rollers therefore roll "downhill" on the locally sheared lining faces, and by traction through radial compression affect shaft rotation. Large traveling waves require thick piezoelectric material, and concomitant high activation potentials. Novelties of the present invention will be shown to concentrate lower potentials by means of electrodes, thereby achieving relatively high electric field intensities which elicit correspondingly larger mechanical wave amplitudes.